This poses a major threat to food security and water resources for agricultural use (Ziervogel et al., 2014). It is therefore known that plants undergoing such a process are drought tolerant (Belko et al., 2012). This has led to the decrease in the land available to small-scale farmers (Fuglie & Rada, 2013; Jayne et al., 2014).
One of the most common cropping systems adopted by small-scale farmers in Africa is intercropping of cereals and legumes ( Rusinamhodzi et al., 2012 ). These include land equivalent ratio (LER), competitive ratio (CR), aggressiveness (A), relative crowding and actual yield loss (AYL) (Yilmaz et al., 2008; Hirpa, 2014). The competitive ratio assesses the LER of each crop in the intercropping system (Dhima et al., 2007).
Relative accumulation evaluates the dominance of one species over the other in the cropping system (Yilmaz et al., 2008). Drivers of climate change include greenhouse gases (GHG) and carbon dioxide emissions (Zargar et al., 2011; Peters et al., 2013). Climate change is the most important constraint on South African livelihoods, especially through food security and water resources (Ziervogel et al., 2014).
Water use efficiency
Anyia & Herzog (2004) observed a strong correlation between RWC and stomatal conductance in cowpea. 2002) reported that stomatal conductance was associated with RWC in teparian beans. When planted under drought conditions, crops with high RWC are able to use water efficiently. 2002) reported that variation in RWC was beneficial in teparian bean lines under water stress. WUE is one of the basic plant traits that gives an indication of crop adaptation to water deficit.
Crops adaptation to drought
Abscisic acid (ABA) and methyl jasmonate (MJ) are among the factors that induce stomatal closure (Belko et al., 2012). Numerous signaling pathways are regulated by sensor and receptor proteins in the membrane (Osakabe et al., 2014). However, other secondary attractive traits also exist in plants, such as drought tolerance, WUE and transpiration regulation (Lu et al., 2011).
Relay intercropping is defined as the cropping system where crop life spans intersect (Sandler et al., 2015). In Mozambique, small-scale farmers usually grow maize with cowpeas or pigeonpeas (Rusinamhodzi et al., 2012). Pigeon pea has an extensive root system (Upadhyaya et al. 2012), which enables it to be more compatible when.
Soil nitrogen availability is also increased for subsequent crops after planting legumes (Dania et al., 2014).
Resources use in cropping systems
- Yield advantage
- Radiation use efficiency
- Land equivalent ratio
- Competition ratio (CR)
The intercropping of cereals such as maize with legumes is beneficial as it increases water use efficiency, soil nutritional status and yields; expressed as soil equivalent ratio (Rusinamhodzi et al., 2012). Radiation use efficiency is defined by Saha et al. 2012) as the radiation light fixed by plants to the ratio of biomass generated. Similar findings were observed by Zhong et al. 2015) in corn-soybean cultivation, where mixtures achieved high RUE under no irrigation.
It is defined as the total area in monoculture required to produce yields that are equivalent to those of interculture (Yilma et al., 2008). The results are similar to those experienced by Zhang et al. 2015) in the corn-soybean and corn-red bean intercrop where the highest LER. Pigeon peas are known to have a deep root system (Upadhyaya et al. 2012), this trait is vital and can enable crop competition in intercropping systems.
According to Kimaro et al. 2009) low interspecific competition between maize and pigeon pea was achieved by legumes.
Weed control
As the impacts of climate change continue to impact agricultural production, adaptations and mitigations are key features in reducing these impacts. The objectives of adaptation and mitigation events should be to reduce the vulnerability of agriculture to drought and climate change. Climate change research is needed to help governments and organizations with policymaking and adaptation processes.
Projections on climate change also reveal changes in annual rainfall and temperature, as well as changes in the growing season and crop production. Effect of water stress applied at different growth stages on seed yield and water use efficiency of pea. Contribution of working group I to the fourth assessment report of the Intergovernmental Panel on Climate Change [Solomon, S.
Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change [Field, C.B. Climate change impact on sub-Saharan Africa : an overview and analysis of scenarios and models / Christoph Müller. Effect of weather on seed yield and radiation and water use efficiency of mustard cultivars in a semi-arid environment.
Approaches to practical adaptive management options for selected water-related sectors in South Africa in a climate change context. An experiment was conducted at Ukulinga Research Farm to evaluate the water use efficiency (WUE) of maize and various legumes in an intercropping system. In South Africa, there is insufficient data on the water use efficiency of certain legumes, such as bambara groundnut, tea bean and pigeon pea.
Such data can thus be decisive for gaining an understanding of the crops' adaptation to climate change and water stress. The aim of this study was to evaluate the water use efficiency of maize (Zea mays) and various legumes in a cropping system.
Site location and experimental design
Climatic data
Plants that reduce their transpiration rate during water stress are considered drought tolerant (Belko et al.
Field preparation and plant material
Data collection and Measurements
Statistical analysis
Leaf gas exchange
Regarding bambara groundnut, there was no significant difference between monoculture and interculture transpiration rates. In terms of maize transpiration rate, there was no significant difference (P > 0.05) between maize monoculture and maize in intercrops of pigeon pea, bean and bambara. Regarding legumes, pigeon pea (12.41 µmol CO2 m-2 S-1) was observed to have the highest rate of photosynthesis compared to intercropping.
There was no significant difference between monocrop and intercrop regarding the photosynthetic rate of cowpea. The intercrops of maize with tepary bean photosynthesis (18.88 µmol CO₂ m-2 S-1) were greater than that of maize in the intercrops of bambara groundnut, pigeon pea and monoculture maize.
Water use efficiency
Soil moisture
Our results are similar to those observed by Cardona-Ayala et al (2013) in cowpea genotypes. Similarly, Mohamed et al (2002) reported that high-yielding lines of Tepar bean reduced stomatal conductance when exposed to drought. Pigeon pea known to perform well in arid and semi-arid conditions (Wilson et al., 2012).
Peas are known to have a deep root system, while maize is characterized by shallow roots (Makumba et al., 2009). In catch crops, the best cropping systems were maize-pigeon pea and maize-tepary bean. In addition, growing population and demand for food production have resulted in more arid lands being cultivated (Singh et al., 2016; Small, 2014).
Intercropping is a practice that involves the cultivation of multiple crops in a field, within the same growing season (Ouma & Jeruto, 2010; Sandler et al., 2015). Maize intercropping is a common cropping system practiced mainly by smallholder farmers on the African continent (Oswald et al., 2002; Marer et al., 2007; Rusinamhodzi et al., 2012). Intercropping of maize with cowpea (Vigna unguiculata (L.) Walp), bambara groundnut (Vigna subterranea (L.) Verdc) and dry beans (Phaselous vulgaris) has been reported in countries such as Nigeria, Kenya and South Africa (Tsubo et al., 2004; Miriti et al., 2012; Dania et al., 2014).
Intercropping legumes with grains can be useful in providing nitrogen (N) to the companion crop (Wang et al., 2014; Mohale et al., 2014), thereby reducing the amount of fertilizer used. This occurs as a result of biological nitrogen fixation, which is achieved through a symbiotic relationship between the crop and specific Rhizobium (Mohale et al., 2014). An increase in soil fertility was observed in an intercrop of maize, wheat and broad beans (Wang et al., 2014).
Intercropping cereal crops such as maize with legumes such as peas is beneficial as it increases yield, land equivalent ratio (LER), water use efficiency, solar energy and soil nutrients (Long et al., 1999; Rusinamhodzi et al. ., 2012). ). The performance of intercropping system is measured by competitive indices such as LER, competitive ratio (CR) and aggressiveness (A) (Dhima et al., 2007; Yilmaz et al., 2008; . Hirpa, 2014).
Experimental design and site description
Plant material
Seeds of tepary beans and pigeon peas (Cajanus cajan (L.) Millsp landrace) were obtained from the University of Zimbabwe.
Field preparation
Data collection
Competition indices
The percentage of maize seedling emergence in bambara groundnut and pea intercrops was similar. For maize, the present results show that maize grain yields in intercrops of pigeon pea, bambara bean and groundnut were not affected by the cropping system. In all cropping systems, the highest and lowest HI was observed in bean and maize monocultures in pea intercrops.
There was no significant difference between the intercrops and the monocrops of bambara groundnut and cowpea with respect to the number of pods per plant (Table 4.4). It was observed that Bambara groundnut had the lowest number of seeds per pod compared to the other legumes. For legumes, the highest competition ratio was observed in bambara groundnut (9.71) and the lowest in chickpea (4.93).
There was no significant difference in the competitive relationship between corn intercropped with tepary bean and green bean. Legumes (tepary bean & legume) had positive aggressiveness compared to bambara which was negative. Intercropping maize with tepary beans had a positive actual yield loss, while maize and Bambar nut had a negative one.
Current results show that tepary beans are early maturing; Bambara groundnut and cowpea are of medium maturity; while pigeon peas are mid- to late-ripening. Bambara groundnut, on the other hand, had the lowest number of pods per plant as well as the number of seeds per plant. The current results differ from those of Alhassan and Egbe (2014) in intercropping maize and Bambara groundnut.
Characterization of bambara groundnut landraces and their evaluation by farmers in the upper western region of Ghana. The highest WUE was observed in pigeon pea monocrops, maize-tepary bean and maize-bambara groundnut intercrops. Tepary beans and bambara groundnuts were affected by the cropping systems as yields of monocropping were higher than those of intercropping.
The maize-black bean intercrop had the highest grain yield, which was greater than maize-tepary bean, maize-bambara and sea leaf maize.
